Mounting means for water chemistry analysis device

ABSTRACT

An improved method of attachment of a pH or p sensor in the recirculation/filtration line for a pool or spa or for forming a T-connection between any two pipes comprises a saddle-clamp modified with an aperture to receive the shank of the sensor with an O-ring and a thinner, harder constricting ring surrounding the O-ring. When the saddle clamp is tightened, the constricting ring forces the O-ring toward the aperture while preventing excessive flattening of the O-ring.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation-in-part of copendingapplication Ser. No. 864,477 filed May 19, 1986, now U.S. Pat. No.4,752,740.

TECHNICAL FIELD

The present invention relates to monitoring systems for the water ofpools, spas, and the like and, more particularly, to a monitoring systemhaving an oxidation-reduction potential (ORP) sensor means disposed inthe water circulating system.

BACKGROUND ART

The growth in popularity of swimming pools, spas, and hot tubs has ledto numerous sanitation problems caused by the difficulty of maintainingthe proper chemical balance in the water. Improperly treated water leadsto the proliferation of germs and bacteria. Similar sanitation problemsalso occur in other reservoirs of water, such as private or semi-publicdrinking water reservoirs, water supply tanks in recreational vehicles,cooling tower systems, etc.

Standard water sanitation methods are based on the use of chemicalsanitizers, such as chlorine, bromine or ozone. In order to beeffective, the sanitizers must be maintained constantly at well-definedconcentration levels in the water, i.e., neither too high nor too low.This is often difficult to achieve in swimming pools and even moredifficult in spas and hot tubs because of the high water temperature andthe use of air jets, both of which tend to rapidly destroy or remove thesanitizer from the water. In addition, when several people get intothese small bodies of water, they produce relatively large quantities ofbody wastes (sweat, etc.) which also deplete the sanitizer.

Pool or spa owners should, therefore, verify the chemistry of the waterbefore anyone enters the water and even after a certain amount of timehas been spent in the water. It is also necessary to add precisequantities of sanitizer as required to maintain the proper and safeconcentration level thereof.

Up to now, the only practical way to verify the chemical balance in thewater of most pools and spas has been with colorimetric chemical testkits using either liquid droplets, test strips or soluble tablets of atype such as that indicated generally as 10 in FIG. 1. In such a testkit, a test sample of water 12 from the pool or spa is scooped into bore14. A staining agent 16 is then added as with the eyedropper 18. Thedegree of staining of the water 12 is determined, theoretically, by theamount of sanitizer in the water. This amount is then determined bycomparing the degree of coloring of the water 12 against that of thepreprinted test scale 20. Such test kits are inconvenient to use,complicated, and not very accurate. They can even give completely falsereadings in case of excess sanitizer due to bleaching of the stainingsolution. As a result, many people neglect the basic testing andchemical maintenance requirements and run the risk of becoming exposedto infections and diseases. These dangerous, unsanitary, and unhealthfulconditions have been noted and reported by health departments all overthe United States, Canada, and Europe, especially in commercial spas andhot tubs, bu also in many swimming pools.

Sophisticated electronic control systems that automatically monitor andmaintain the chemistry of the water have been successfully manufacturedand marketed for many years by several different companies; however,these devices are too expensive and too complicated for non-technicalpeople and the average homeowner or small user. They also require asignificant amount of maintenance, particularly for the chemicalfeeders. Consequently, they are used almost exclusively on large poolsand spas, and not on the hundreds of thousands of smaller installations,commercial or residential, that need this type of protection just asmuch as the larger ones.

Recently, sanitarians at this year's National Environmental HealthAssociation annual meeting were told that oxidation-reduction potential(ORP)--a mandatory standard for measuring water quality in WestGermany's public pools and spas--ought to become a public healthrequirement in the United States.

Of related interest, a recently completed study of chemical andmicrobiological water-quality constituents for thirty public spas in thearea of Portland, Oreg., found little correlation between thefree-chlorine residual readings normally used to monitor them and thebacteriological quality of the spas themselves.

Normally, it is presumed that if you are maintaining a free-chlorineresidual of two milligrams per liter or two parts per million (2 ppm),you have good water quality; but, the above-referenced test did not findthis to be true. The only parameter that seemed to take intoconsideration all the constituents, including oil and greaseconcentration, was ORP. It was found that whenever the ORP residual wasequal to or greater than 650 millivolts, the water was bacteriologicallyacceptable.

The National Sanitation Foundation (NSF) task committee that iscurrently reviewing pool and spa equipment standards, has pointed outthat ORP is a well-known measurement in the field of sewage waste-watertreatment. People who are knowledgeable in that area are franklysurprised that ORP is not being used for the monitoring and control ofpools and spas. Public spas, in particular, are a prime target for ORPbecause organic loading makes potential disease transmission far moresignificant for public spas than for pools.

The above-referenced report suggests that bather loading, ORP, andchlorine effectiveness are directly related. The OTO chlorine test kitof FIG. 1 which is routinely sold in pool stores is unreliable becauseit fails to distinguish between free and combined chlorine. Theparts-per-million reading determined from the stain comparison canactually be a reflection of combined chloramine, which does not protectbathers from bacteria and viruses.

Because organic and chemical loading significantly reduces the abilityof free chlorine to overcome bacteria, DPD free chlorine test kits arealso of questionable value unless the exact level of organic contaminantand the pH in the spa water can be determined.

West Germany's public health standards produce pool and spa waterquality in that country which meets or exceeds Environmental ProtectionAgency drinking water standards in the United States. In West Germany,free chlorine levels of 0.2 to 0.4 ppm are considered more than adequateas long as the ORP is at an acceptable level of 650 millivolts orhigher.

ORP is defined as the oxidation-reduction potential of a sanitizer suchas chlorine, bromine or ozone. These oxidizers "burn off" impurities inthe water, including body wastes, algae and bacteria. An ORP sensormeasures the potential generated by the active form of the sanitizer,and not the inactive forms, such as combined chlorine. Unlike OTO or DPD"eyeball" testing as described above, ORP is an ongoing electronicprocess that requires no test chemicals or reagents and constantlymonitors sanitation levels.

Persuading pool and spa industry people and public health officials torely on ORP is a question of education and cost. NSF predicts theeventual adoption of an ORP standard for public and semi-public pool andspa facilities. Currently, a handful of manufacturers produce ORPprobes, usually as a component of an automated chemical feeder system.Ironically, even managers of pools and spas who swear by chemicalautomation usually are unaware that ORP metering is built into thesesystems; the acronym is anything but a household word. ORP probes pricedin the $80-100 range are now available and can monitor water on acontinuous basis.

In some places, chemical automation is already mandatory. In WarrenCounty, Ohio, for example, the General Health District requiresinstallation of an electronic water-control device on all public spasand hot tubs to monitor and control free chlorine and pH. The same istrue in Anchorage, Ak., where an automatic chlorinator with a sensor isrequired to insure proper levels of chlorine.

In a 1984 study in San Diego that included health club and condominiumspas, out of fifty public spas surveyed, the researchers found that 24%of them were a source of parasitic infection and that more than 50% ofthem were under-chlorinated and had unhealthful bacteria. Thus,regardless of the costs, it is obvious that something must be done toguarantee the healthfulness of pools and spas on all levels.

STATEMENT OF THE INVENTION

The present invention provides a low cost system incorporating the ORPstandard for monitoring pools, spas, and the like.

The inventive monitor for pools, spas, and the like, that can be used tohandle complex electronic signals and convert them into simple readoutsand operating instructions without costly and complicated electroniccircuitry.

The monitoring system of the present invention for pools, spas, and thelike includes a container filled with water for holding one or morebathers therein and a recirculating system for removing water from thecontainer, filtering it, and returning it to the container. Themonitoring system comprises, oxidation-reduction potential (ORP) sensormeans disposed in the recirculating system for developing at an outputthereof an electrical signal directly related to the active form of asanitizer contained in the water; pH (PH) sensor means disposed in therecirculating system for developing at an output thereof an electricalsignal directly related to the acidity/basicity level of the water; afirst bargraph display; a second bargraph display; first electricaldriver means operably connected between the output of the ORP sensormeans and the first bargraph display for moving the first bargraphdisplay in step increments between upper and lower limits correspondingto "more than necessary" and "less than necessary" levels of sanitizerin the water; second electrical driver means operably connected betweenthe output of the PH sensor means and the second bargraph display formoving the second bargraph display in step increments between upper andlower limits corresponding to "lower acidity than optimum" and "higheracidity than optimum" levels of water; first scale means disposedadjacent the first bargraph display for indicating the millivolt signalfrom the output of the ORP sensor means and for indicating portions ofthe first bargraph display wherein sanitizer should be added to thewater when the first bargraph display is indicating therein; and, secondscale means disposed adjacent the second bargraph display for indicatingthe pH corresponding to the electrical signal from the output of the PHsensor means and for indicating portions of the second bargraph displaywherein acid should be added to the water and base should be added tothe water when the second bargraph display is indicating therein.

The present invention also relates to a simplified method for attachmentof a sensor to the recirculating line. Attachment of sensors (usually1/2 inch in diameter) on a pool or spa recirculation line (normally 11/2or 2 inches in diameter) by conventional methods constitutes a majorplumbing problem involving cutting of the line, insertion and glueing orsoldering of a reducing tee and insertion of a compression fitting. Thiswork is too complicated for most homeowners and normally requires costlyprofessional installation.

A simplified and inexpensive method of attachment of the sensor madepossible by the invention permits free installation of the sensor bymost homeowners, or at minimal cost by a professional installer.

The method of the invention only requires drilling of a 1/2-inch hole inthe pipe and mounting of the sensor with a specially designed saddleclamp and O-ring assembly.

The seal is formed by an O-ring that fits tightly around the body of thesensor. A constricting ringlet around the O-ring prevents its expansionwhen it is compressed by the saddle clamp. Previous attempts to use anO-ring without the constricting ringlet resulted only in leaks andfailure of the recirculation system. The present system is veryeffective and works practically every time, thus saving considerabletime and money in installation.

Obviously, the present invention is also applicable to any size pipe orany diameter sensor. The attachment method is not limited to pools andspas. It is useful in joining any pipe to any other pipe carrying aliquid or gaseous fluid. The T-joint can be used to meter or inject onefluid into another fluid or simply to form a branch juncture. Forexample, the modified clamp of the invention could be used to tap an icemaker line into an existing water line.

These and many other features and attendant advantages of the inventionwill become apparent as the invention becomes better understood byreference to the following detailed description when considered inconjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified drawing of a prior art pool water test kit of thetype wherein a visual determination of sanitizer level is made bycomparison of staining level to a preprinted color scale;

FIG. 2 is a simplified block diagram representation of the monitoringsystem of the present invention;

FIG. 3 is a detailed drawing of the display panel for the commercialembodiment of the monitoring device of the present invention with ORPmillivolts and pH scales;

FIGS. 4A and 4B is the electronic circuit employed in the commercialembodiment of the present invention of FIG. 3;

FIG. 5 is a display panel for the monitoring device of the presentinvention in an alternate embodiment having ppm free chlorine and pHscales;

FIG. 6 is a graph of curves showing the relationship between ppm of freechlorine and ORP millivolt readings as a function of pH in the absenceof cyanuric stabilizer as used to prepare the scales used in conjunctionwith the linear bargraph displays of the present invention;

FIG. 7 is a graph of curves showing ORP millivolts v. pH for the activeform of free chlorine as would be used in preparing the dual scale shownin the embodiment of FIG. 5;

FIG. 8 is a schematic view of an assembly for mounting in a sensor in arecirculating line;

FIG. 9 is a cross-section taken along line 9--9 of FIG. 8; and

FIG. 10 is a further view in section taken along line 10--10 of FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The monitoring system of the present invention, to be described indetail hereinafter, uses the same type of electronic sensors that areused on the more expensive automatic controllers for pools or spas.These sensors are called ORP and pH electrodes and they can be purchasedfrom many different manufacturers in the United States and overseas,such as the Broadley-James Corp. in Santa Ana, Calif. As less costlysensors become available, they can be substituted for the more costlysensors presently available to thereby provide the advantages of thepresent invention at an even lower cost. These sensors monitor thesanitizer and the pH level in the water and produce electronic signalsthat vary with the chemistry of the water. In the present invention,these signals are electronically converted by an amplification circuitand then displayed on linear bargraphs. Customized indicating scales arelocated next to the bargraphs. These scales are used to show thechemical concentration levels in simple non-technical terms and,additionally, to directly convey operating instructions for manualcontrol of the water sanitizing and other conditioning chemicals ineasy-to-understand language.

A preferred embodiment of the present invention as manufactured and soldcommercially by applicant s company under the trademark AQUASENSE isshown and generally indicated as analyzer 22 in FIG. 2. As can be seenfrom the system diagram of FIG. 2, the ORP and pH sensors 24 and 26,respectively, continually sense the circulating water and are connectedby wires 28 and 30, respectively, to the AQUASENSE analyzer 22, where adual bargraph liquid crystal display 32, to be described in detailshortly, includes both a pH scale from 7.2 to 7.8 and an ORP scaleshowing millivolts (mV) of oxidation-reduction potential for thesanitizer from 500 mV to 900 mV. As should be readily recognized fromthe simplified drawing of FIG. 2, the monitoring system of the presentinvention has a major advantage over the prior art "eyeball" testsnormally used with home spas and pools in that the water being sensed isnot a fixed volume (which is normally dipped out of the pool at the topand near an edge and not necessarily representative of the majority ofwater volume), but rather, a constant monitoring of the water passingthrough the recirculation pipe 34 from the pool or spa leading into thepump 36, filter 38, heater 40, and back to the pool or spa.

As shown in FIGS. 8-10, the pH and water sensors 24, 26 are readilyinstalled in the recirculation line 34 with the clamp assembly 200 ofthe invention. The assembly 200 includes a saddle clamp 202 having acircular aperture 204 with a diameter equal to the diameter of the shank206 of the sensor 24, 26 and an O-ring 208 and a constricting ringlet210. The clamp includes the conventional slotted belt 212 having one end214 engaging a tightener bolt 216 carried in a sleeve 218. The O-ring208 has an inner diameter such that it fits tightly onto the shank 206of the sensor. The constricting ringlet 210 has an inner diameter justlarger than the outer diameter of the O-ring 208 such that the O-ring208 loosely fits within the ringlet. The ringlet 210 is formed of a muchmore rigid material than the elastomeric O-ring, suitably the ringlet isformed of an engineering plastic such as Nylon (a polyamide) The ringletcan have a circular or rectangular cross-section. A flat ringlet isreadily fabricated by slicing a ringlet from a length of tubing. Theringlet must have a height less than the O-ring to allow compression ofthe O-ring to seal the sensor into the line. Suitably, the ringlet has aheight from 40% to 60% of the diameter of the O-ring.

The sensors are installed by drilling two holes 220 in the recirculatingline 34 having a diameter equal to the diameter of the shank of thesensors.

Before drilling the holes, make sure to stop the recirculation pump anddrain the water if the pump is below the water line. Select a properlocation for each sensor, i.e. before the pump, on top of the pipe andat least 3 inches apart. Using the 1/2-inch auger bit, drill two holesso that the sensors (with cap removed) can slide in easily. Do notoverdrill the holes as this could result in air leaks and cause pumpdamage. Remove the protection caps at the tip of the sensors and storethem in a safe place for winterizing or for possible reshipping of thesensors. Carefully insert each sensor 24, 26 through the aperture 204 inthe steel clamp 202, one O-ring 208 and a constricting ringlet 210.Adjust this assembly on the sensor so that the tip 222 of the sensorwill be positioned approximately in the middle of the pipe 34. Insertthe sensor 24, 26 in the pipe and tighten up the clamp just enough totake up the slack of the strap. Overtightening may cause air leaks. Alsomake sure that the loose end of the strap does not cut into the sensorbody. The pump is primed and run to check for leaks around the sensors.If there is a leak, tighten up the clamp screw one or two more turns oradd some silicone sealant.

As mentioned earlier, ORP is directly related to the concentration andactivity of the sanitizer in the water and has been recognized byinternational health authorities as a good indicator of water quality.In 1972, the World Health Organization recognized in their Standards fordrinking Water that at an ORP level of 650 millivolts, the water isdisinfected and viral inactivation is almost instantaneous. In theAQUASENSE analyzing system of the present invention, the ORP readings inmillivolts are translated at the display 32 into simple instructions forthe homeowner or serviceman to show whether the water is safe andwhether chemicals need to be added. The display 32 of the presentinvention in its commercial embodiment is shown in greater detail inFIG. 3. Bar graph displays at 42 and 44 are used to display the ORP andpH readings, respectively. Scales 46 and 48 disposed adjacent to thedisplays 42, 44 provide the homeowner or service technician with adirect and easily understood indication of the ORP and pH levels,respectively, along with a direct indication of what action is to betaken, if any. The advantages of using an ORP scale at 46 instead of themore familiar parts-per-million (ppm) of free chlorine is that ORP isdirect reading, does not need calibration, and applies to all sanitizersor combinations of sanitizers. In addition, it automatically reflectsthe effects of pH and other chemicals such as cyanuric acid stabilizeron the activity of the sanitizer.

The electrical diagram for the AQUASENSE analyzer 22 in its commercialembodiment is shown in FIGS. 4A and 4B. The values of the componentsthereof are listed in Table I. For use around a pool/spa environment,the electrical switches and contacts to be described are of theso-called "membrane" variety and are disposed behind flexible portionsof the panel 56 of the display 32 of FIG. 3. The operation of thecircuitry of FIGS. 4A and 4B should be readily understood by thoseskilled in the art from an inspection thereof and, therefore, in theinterest of simplicity of this application, the details thereof will bediscussed broadly and not in minute detail.

                  TABLE I                                                         ______________________________________                                        ITEM       VALUE       ITEM     VALUE                                         ______________________________________                                        R1         1 M ohm     R2       100K ohm                                      R3         1.47 M ohm  R4       365K ohm                                      R5         2.98 M ohm  R6       732K ohm                                      R7         182K ohm    R8       100K ohm                                      R9         6.8 M ohm   R10      10 M ohm                                      R11        4.7K ohm    R12      205K ohm                                      R13        100K ohm    R14      383K ohm                                      R15        412K ohm    R16      118K ohm                                      R17        20.5K ohm   R18      301K ohm                                      R19        120K ohm    R20      25.5K ohm                                     R21        6.8 M ohm   R22      1.15K ohm                                     R23        37.4K ohm   R24      20K ohm                                       R25        100K ohm    R26      130K ohm                                      R27        10 M ohm    R28      4.7K ohm                                      R29        100K ohm    R30      200K ohm                                      R31        49.9K ohm   R32      100K ohm                                      R33        11.3K ohm   R34      45.3K ohm                                     R35        2 M ohm     R36      2 M ohm                                       R37        6.8 M ohm   R38      1.8K ohm                                      R39        4.99K ohm   R40      4.99K ohm                                     R41        100K ohm    R42      4.99K ohm                                     R43        25.5K ohm   R44      8.66K ohm                                     VR1        2K ohm      C1       47 Nfd                                        C2         10 Nfd      C3       10 Nfd                                        C4         10 ufd      C5       1 Nfd                                         C6         (unused)    C7       4.7 ufd, 16 V                                 C8         3.9 ufd, 16 V                                                                             C9       47 ufd, 16 V                                  C10        4.7 ufd, 16 V                                                                             IC1      4060                                          IC2        3240A       IC3      3240A                                         IC4        MCI 4040    IC5      74C906                                        IC6        393         IC7      LM336Z-5.0                                    IC8        IR 2429     IC9      IR 2429                                       Q1, Q3, Q4 VN2222L     Q2, Q5   VP0300L                                       All Diodes 1N914                                                              ______________________________________                                         Where:                                                                        ufd = microfarad = 1 × 10.sup.-6 farad                                  Nfd = Nanofarad = 1 × 10.sup.-9 farad                              

The voltage of the 9 volt battery 50 is continuously applied tointegrated circuits IC1 and IC4 (52 and 54, respectively) so that therun timer IC1 is standby powered and the pH probe calibratecounter/memory retains its current value.

When the [TEST] contact pad 58 is pressed, IC1 (52), anoscillator/counter, is initialized to zero, turning on the powersupplyto +8 volts. Releasing the [TEST] pad 58 allows IC1 (52) to oscillateand count. After approximately 30 seconds, IC1 (52) will shut off the +8volts and prevent itself from oscillating until once again it is resetby pressing the [TEST] pad 58. The object of the timing and automaticshutoff is to conserve battery power and increase its longevity betweenreplacements. This part of the circuit can be eliminated or bypassed ifthe unit is connected to a constant power supply instead of anexpendable battery as shown.

When the +8 volts is on, IC7 (60) sets 5.00 volts difference between the4.0 and the -1.0 regulated voltages. IC2a (62) provides a low impedancesource for zero volts (circuit reference or "ground"). Other bias andtest voltages are derived from the resistor dividers at 64.

The electronic signals from the two sensors 24, 26 at ORP IN and PH IN,respectively, are filtered then buffered by the non-inverting amplifiersIC2b and IC3b (66, 68), respectively.

On the ORP side, feedback and bias resistors cause the ORP signal to beconditioned to the proper range for displaying on the left side bargraph42 of the liquid crystal display, which is 500 to 900 millivolts fullscale. IC8 (70) converts the input DC voltage level to the format of theliquid crystal display bargraph 42.

On the pH side, the output of the pH amplifier is one input to a summingjunction. The other input to this junction is the pH probe calibrationoffset current. This current and the pH buffer/amplifier signal areconditioned by IC3a (72) to be in the proper range for displaying on thebargraph 44 on the right side of the liquid crystal display, in thiscase 0 to -50 millivolts. IC4 (74) is a binary up-counter. It isincremented when the two contact pads 76 and 78, marked [CAL] and [PH],respectively, are pressed simultaneously. As this counter increments,IC5 (80) switches the five resistors 82 between -1.0 volt and an opencircuit. Since the resistors 82 are normally connected to theaforementioned summing junction, the voltage to be displayed can beraised incrementally. The values of the resistors are chosen to produceincrements of 10% on the display. IC9 (84) converts the input DC voltagelevels to the format of the liquid crystal display bargraph 44.

When the [ORP CHECK] contact pad (86) is pressed, a fixed voltage forcesthe probe buffer input to a predetermined value of 650 millivolts sothat the buffer and display circuits operation can be checked.

When the [PH CHECK] contact pad 88 is pressed, a fixed voltage forcesthe probe buffer input to a predetermined value of -30 millivolts. Toassure the predetermined value, the pH probe offset is also forcedtemporarily to its center value.

When the [BAT CHECK] contact pad 90 is pressed, both ORP and pH voltagesat the display section inputs are initially clamped to a low value (offscale downward) by IC6a (92). At the same time, both ORP and pH voltagesto the display 32 are forced to maximum by IC6b (94). Two seriesresistors prevent excess current from flowing. If the battery voltage ishigh enough, the downscale clamp is released after a short delay and thedisplay section now receives full upscale voltage. The result is aninitial blank display then full scale display if the battery is good.

In another possible embodiment of the present invention, the scalecorresponding to the electronic signal from the oxidation-reductionpotential (ORP) electrode 24 is labeled in parts-per-million (ppm) offree chlorine as shown in FIG. 5. The electronic signal (in millivolts)generated by the ORP electrode 24 varies in a complex manner with theconcentration (ppm) and chemical form of the sanitizer in the water. Italso varies with the pH of the water and with the concentration of otherchemicals that may be present in the water; for instance, cyanuric acid,a stabilizer that is commonly used to protect chlorine fromdecomposition by the ultraviolet rays of the sun.

The set of curves shown on FIG. 6 give a representation of the sensorsignal as a function of chlorine concentration and pH level. One can seethat each curve varies non-linearly in a very complex manner and that awhole set of curves is required to represent the effect of variations inpH level. In addition, these curves are valid only when there is nocyanuric stabilizer in the water. If there is a cyanuric stabilizer inthe water, one needs a complete set of curves for each differentconcentration level of stabilizer. To date, nobody has even attempted todetermine these curves. In other words, the complexity of therelationship between the electronic signal of the sensor and thechemical conditions in the water is impossible to representmathematically and would be very difficult and expensive to reproduceelectronically. This is one of the reasons why there is no electronicmonitoring device of this type on the market today.

In the embodiment of FIG. 5, the linear bargraph display 42' for thesanitizer is used to show the variations of the sensor signal. Insteadof converting the signal electronically however, the conversion is madegraphically with a non-linear scale 46' which is placed adjacent thebargraph display 42'. The scale 46' is determined from curves such asthose on FIG. 6. The user needs only to calibrate the unit and then readthe variations in sanitizer and pH levels on the scales. The preferredmethod for calibration of the pH scale is to place the pH sensor inwater of known pH value, preferably a buffer solution of fixed pH value.If no such solution is available, the water of the pool or spa can beused after its pH value is determined with a reliable pH test kit, suchas a Phenol Red solution.

One additional advantage of linear bargraph displays as employed in thepresent invention is that they look very similar to the colorimetricscales that are used with chemical test kits. Most pool or spa ownersare familiar with these scales and it is therefore easy for them tointerpret the linear bargraph scales.

As also shown on FIG. 5, the same bargraph display 42' can also be usedfor two different chemicals with different rates of variationrepresented by different scales incorporated as part of the scale 46'.In this instance, the bargraph display 42' on the left side is used withtwo separate scales, one for chlorine (96) reading from 0.5 to 5 ppm(parts-per-million or milligrams per liter) and one for bromine (98)reading from 1 to 10 ppm. Note that both sanitizer scales 96, 98 arevery precisely calculated form curves such as those shown in FIG. 7.They are non-linear, i.e., the distance between 1 and 2 ppm(parts-per-million) is greater than the distance between 3 and 4 andeven still greater than the distance between 8 and 10.

As one important aspect of the present invention, it should be notedthat simple instructions, as at 100, have also been added to the scales42' to advise the user either that the concentration level isappropriate or that corrective action should be taken and what thatcorrective action should be. The specific nature of the correction isindicted directly on the scale; such as "add acid", "add base", "addchlorine", etc. Years of experience in the pool and spa industry haveshown that non-technical people are easily confused and afraid to usechemical concepts such as pH values or ppm levels using numbers shown onmeters or digital readouts. The present invention eliminates thisproblem by providing simple instructions in everyday language. Ifdesired, of course, it can also be used to show common chemical names ortrade names of specialty chemicals. The fact that the AQUASENSE analyzerof the present invention described herein shows the user how to correctfor improper water chemistry but does not actually feed the chemicals isimportant because it eliminates the problems caused by chemical feeders.Therefore, this makes it practically maintenance-free, the onlymaintenance required being the cleaning of the sensors if they becomedirty. This also results in very low power consumption, which means thatthe device can be operated for a year or more on small battery power anddoes not require any electrical wiring.

While the analyzing system of the present invention is intendedprimarily for use by homeowners and small commercial users, it can alsobe used conveniently by pool and spa servicemen for quickly andaccurately testing of water quality. By eliminating the need forcalibration, the unit can be made portable and the ORP reading can beused on different pools and spas to determine the quality of the water.If the ORP reading is above a certain level, say 650 millivolts, theserviceman knows that the water meets the standards for drinking water.If it is below that level, he knows that he must add more sanitizer orcheck the pH and cyanuric acid levels.

The bargraph display described above which is incorporated into thepresent invention is a high-technology electronic device which can bemade easily with a liquid crystal display or a set of light emittingdiodes. For battery operation as shown in the example described herein,liquid crystal displays are preferred since they have much less currentdrain when used with battery operation.

Thus it can be seen that the present invention provides a new and novelwater analysis system for use with pools, spas, and the like, whichprovides much more accurate information, ease of operation, and directinstructions on corrective action to be taken, if any, than availablewith analysis systems according to the prior art.

It is to be realized that only preferred embodiments of the inventionhave been described and that numerous substitutions, modifications andalterations are permissible without departing from the spirit and scopeof the invention as defined in the following claims.

I claim:
 1. A water analysis system for continuously analyzing the waterin a recirculating line for pool, spa or the like, comprising incombination:a set of adjacent sensors for mounting in said line saidsensors including: a cylindrical shaft surrounding each of said sensors;a first oxidation-reduction potential (ORP) sensor mounted on the wallof the line with a sensing probe dispersed in the water in the line fordeveloping a first electrical signal at its output directly related tothe active concentration of the form of an oxidation sanitizer containedin the water; a second pH sensor mounted on the wall of the line with asensing probe dispersed in the water in the line for developing a secondelectrical signal at its output directly related to the acidity/basicitylevel of the water in the line; means for mounting each of the probes onthe wall of the line including an aperture through said wall forreceiving the shaft, an assembly of an inner O-ring and an outerconstricting ring slidably mounted on the shaft, said constricting ringbeing harder than the O-ring and having a height smaller than thediameter of the O-ring slidingly positioned on the outside edge of theO-ring and a belt clamp having an aperture receiving the shaft of thesensor and having a belt surrounding the line and means for tighteningthe belt clamp whereby the clamp flattens the O-ring between the beltand the wall of the line while it is constrained by the outerconstraining ring; an analyzer unit having a housing covered by a faceplate and including: a first bargraph display having a visual indicatormovable over a first range corresponding to concentrations of sanitizerbelow and above optimum concentration mounted on said face plate; afirst sanitizer scale having a height equal to said first range printedon the face plate adjacent the first bargraph display indicating in thebelow optimum portion of the range a printed instruction to addsanitizer; a second bargraph display having a visual indicator movableover a second range corresponding to pH mounted on said face plate; asecond scale printed on the face plate adjacent the second bargraphhaving a height equal to the second range including printed instructionin the high pH range to add acid and a printed instruction in the low pHrange to add base; a compartment within said housing for receiving abattery; first electrical driver means electrically connected to saidbattery compartment and operably connected between the output of saidfirst sensor and the first bargraph display for moving the firstbargraph display in step increments over the first range; and secondelectrical driver means electrically connected to said batterycompartment and operably connected between the output of the secondsensor and the second bargraph display moving the second bargraphdisplay in step increments over the second range.
 2. The improvement toa water analysis system of claim 1 wherein:(a) said first electricaldriver means is adapted to drive said first bargraph display betweenupper and lower limits of 900 mV and 500 mV; and, (b) said secondelectrical driver means is adapted to drive said second bargraph displaybetween upper and lower limits corresponding to pH values of 7.8 and7.2.
 3. The improvement to a water analysis system of claim 2wherein:said first scale means disposed adjacent said first bargraphdisplay for indicating the millivolt signal from the output of the ORPsensor includes indicia calibrating said first scale to indicateparts-per-million of free chlorine.
 4. The improvement to a wateranalysis system of claim 3 wherein:said first scale means disposedadjacent said first bargraph display for indicating the millivolt signalfrom the output of the ORP sensor includes indicia calibrating saidfirst scale to indicate the presence of two different sanitizers.
 5. Theimprovement to a water analysis system of claim 4 wherein:said firstscale means includes first indicia reading from 0.5 to 5 parts permillion for indicating the presence of chlorine and second indiciareading from 1 to 10 parts per million for indicating the presence ofbromine.
 6. In a pool or a spa having a line for recirculating a waterstream in which a chemical sensor having a tubular shaft, carrying asensing element is received, the improvement comprises:means forsealingly mounting the sensor in an aperture in the line with thesensing element disposed in the water stream in the line; an assembly ofan outer constricting ring and an inner O-ring with the O-ring slidinglymounted on the shaft; said constricting ring having a greater hardnessthan the O-ring and a smaller thickness than the O-ring; a cylindricalbelt clamp surrounding the line having an aperture for receiving theshaft with the assembly of the O-ring and constriction ring disposedbelow the surface of the belt; and means attached to the clamp fortightening the belt whereby a compression force is applied to the O-ringwhich flattens the O-ring between the outer surface of the line and theinner surface of the belt as constricted by the outer ring and seals theshaft in the aperture in the line.
 7. The sensor mounting means of claim6 in which the O-ring is an elastomer and the constricting ring is arigid, engineering plastic.
 8. The sensor mounting means of claim 6 inwhich the constricting ring has a height smaller than the diameter ofthe O-ring.
 9. The sensor mounting means of claim 8 in which theconstricting ring is formed of Nylon.
 10. A coupler for forming aT-connection between a first pipe and a second pipe, said first pipehaving an aperture for tightly receiving the second pipe;an assembly ofcompressible O-ring and an outer adjacent constricting ring received onthe second pipe; said compressible O-ring having an inner diametersubstantially equal to the outer diameter of the second pipe; saidconstricting ring being formed of a harder, less compressible materialthan the O-ring; having an inner diameter substantially equal to theouter diameter and having a height less than the diameter of the O-ring;a flat ring clamp having an opening for receiving the second pipeencircling the first pipe with said assembly being positioned betweenthe lower surface of the ring clamp and the outer surface of the firstpipe; and means for tightening the clamp around the first pipe wherebysaid O-ring is compressed to seal the aperture in the first pipe.
 11. Acoupler according to claim 10 in which the tightening means comprises aseries of axial slots on the ring clamp and a threaded bolt mountedadvance the clamp past the bolt on rotation of the bolt to reduce thecircumference of the clamp.
 12. A coupler according to claim 10 in whichthe first pipe is formed of a synthetic resin.
 13. A coupler accordingto claim 12 in which the first pipe is formed of polyvinyl chloride.